This invention relates to gauge used with a disc pad and caliper piston checking to indicate excessive wear to a pad. It is employed without removing the tire and wheel assemblies of the vehicle. Particular application is found when the vehicle is subject to a lot of stop and go travel, such as that normally encountered by school buses and other street maintenance vehicles, where disc brake pads wear more due the heat and friction generated in this type of driving.
Wear indicators for disc brake systems or their pads are known. In one such invention an insertion hole for the indicator extends through a backing plate and into the pad for a distance equal to the length of the wear indicator. When the pad is worn away a sufficient amount the electrically conductive indicator is encountered by the disc and an alarm is generated. In another prior art invention, the brake wear indicator a prong and flange combination is used. When the prong engages a rotating disc or drum, the flange vibrates to generate an audible warning signal.
Still another invention discloses a disc brake with a stationary member secured to a non-rotatable part of a vehicle and a friction pad disposed on each side of the rotatable disc. A wear warning piece has one end secured to the stationary member and its other end extending between the disc and a backing plate of the friction pad by a predetermined distance. As wear occurs to the pads, the indicator is eventually contacted by the backing plate in applying the brakes resulting in a keen vibrational noise.
A more recent invention uses a visible wear indicator to indicate the remaining usable thickness of the brake block used in a drum brake system. The indicator is molded integrally in the brake block and has a safe surface indicated and a minimum safe point.
The present invention is a visual wear indicator for a disc brake system utilizing one caliper mounted gauge at each vehicle wheel all as will be described in detail hereafter.